[PATCH][AArch64] LR register not used in leaf functions

Kugan kugan.vivekanandarajah@linaro.org
Mon Sep 22 15:43:00 GMT 2014


AArch64 has the same issue ARM had where the LR register was not used in
leaf functions. This was reported in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42017. In AArch64, this
test-case need to be added with more live ranges for the need for the
LR_REGNUM. i.e test-case in the PR needs additional loops up to r31 for
the case AArch64 to see this.

The same fix (from the thread
https://gcc.gnu.org/ml/gcc-patches/2011-04/msg02191.html) which went
into ARM should apply to AArch64 as well. Regression tested on qemu for
aarch64-none-linux-gnu with no new regressions. Is this OK for trunk?

Thanks,
Kugan


gcc/ChangeLog:

2014-09-23  Kugan Vivekanandarajah  <kuganv@linaro.org>

	* config/aarch64/aarch64.h (EPILOGUE_USES): Return true only after
	epilogue_completed is true.
-------------- next part --------------
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index db950da..b3e4585 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -309,7 +309,7 @@ extern unsigned long aarch64_tune_flags;
    considered live at the start of the called function.  */
 
 #define EPILOGUE_USES(REGNO) \
-  ((REGNO) == LR_REGNUM)
+  (epilogue_completed && (REGNO) == LR_REGNUM)
 
 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
    the stack pointer does not matter.  The value is tested only in


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